After nearly 100 years, the National Park Service holds some of the country's most beautiful and historic places. It also suffers from an $11 billion backlog of unfunded maintenance and a visitor base that's aging and mostly white.

With its centennial approaching in 2016, the park service is launching a campaign to raise support and court a younger, more diverse visitor base. First lady Michelle Obama and former first lady Laura Bush will co-chair the campaign. The campaign will call on Americans to "Find Your Park."

Sustaining the parks and keeping them relevant to visitors far into the future is a challenge, park officials said. Many facilities date back 50 years or more. Some are in danger of failing, such as a 70-year-old water pipeline at the Grand Canyon. The pipeline breaks regularly and could cut off the water supply to the site, National Park Service Director Jonathan Jarvis said. Lodging at Glacier National Park needs a major overhaul. The nearly 100-year-old Memorial Bridge in Washington needs at least $150 million in repairs. That's more than the agency's entire annual construction budget.

Behind the scenes, officials are seeking to expand fundraising through the National Park Foundation. They also want to bolster congressional support to improve the parks.

This is the third major campaign in the national parks' history. An outcry over deplorable park conditions in 1915 originally led to the creation of the National Park Service. In the 1950s, there were calls to close parks because of their neglected conditions. That inspired a campaign to rebuild infrastructure and invite returning World War II veterans and their families to visit parks. The memorable slogan "See the USA in your Chevrolet" was created.

"They came in droves, and in the back seat of that station wagon in the national parks were today's boomer generation," Jarvis said. "They are our base today... The question that we're facing is who's going to be the next generation of park supporters."

The national parks counted 292 million visitors in 2014. But there is a problem. Those visitors tend to be older and whiter than the U.S. population overall.

"If we were a business and that was our clientele, then over the long term, we would probably be out of business," Jarvis said.

In studying public perceptions, park officials found many people think national parks are only in the West, such as Yellowstone and Yosemite. They want people to understand that urban sites such as the Statue of Liberty, Independence Hall in Philadelphia, Little Rock, Ark., Central High School and the Lincoln Memorial in Washington are also national parks.

Over the next year, an advertising campaign will show how people connect with their favorite parks. Corporate sponsors including American Express, REI and Humana also are supporting the effort.

To broaden access to the parks, all fourth grade students and their families will get free admission to national parks during the next school year.

President Barack Obama requested an increase of $432 million to support the National Park Service in his 2016 budget proposal. It's a sustained request that would lift the agency's budget to $3 billion annually. The money would address deferred maintenance and other needs but likely will face resistance in Congress.

During a recent hearing, Republican Rep. Tom McClintock of California said Congress must ensure the parks are well maintained. However, he said the park service is plagued by "a clash of visions." The issue is between open access and new policies limiting access or amenities in some areas. He said the agency should be cautious about naming new parks before it fixes the ones it already has.

A campaign is under way to raise hundreds of millions of dollars to rebuild historic infrastructure with private funds. Campaign planners hope public support will also help build congressional support.

"If we don't reach out and become relevant to a broader population, we won't have the support the parks need to do their jobs in the future," said Interior Secretary Sally Jewell.

Critical thinking challenge: Why have supporters focused their efforts on seeking funds from private and corporate sponsors, rather than Congress?